Believing sinners differ from unbelievers: they can do good works from faith
This is seen in Jansenius, On the state of fallen nature, book 4, chapter 4. 'Although it is most true,' he says, 'that the works of all sinners, and even of the righteous, which are not referred to the end to which they ought to be referred, that is, to God, but stick fast in creatures, are true sins, it is false that the case is the same for believing sinners as for unbelievers.
For by the very fact that sinners are imbued with faith, even though they lack that perfect charity which loves God above all, that is, justification, they can still do many good things from that faith: first of all, believing itself and willing to act, and, if they still lack the strength, groaning over their weakness and obtaining from faith justification or the strength to act. Augustine always ascribes works of this kind to sinners.'
Later, wishing to prove that believers, however enslaved to sins, do not lack a certain imperfect love of God, which is nonetheless sincere and the beginning of true piety, a love of God that unbelievers wholly lack, he says: 'By the very fact that they still remain believers they cannot fail to have that affection of true piety and love from which they believe God, from which they hope for blessedness in due course, from which they pray to obtain perfect charity and righteousness, and from which they also do some other good things with a sincere regard to God, although they do not yet love him so as to prefer him to all earthly loves and delights.'
Latin
XLVII. Istud videre est apud Jansenium De statu naturae lapsae libro quarto capite quarto. Nam, inquit, quamvis verissimum sit opera peccatorum omnium, imo etiam justorum, quae non referuntur ad eum finem ad quem referri debent, hoc est, ad Deum, sed in creaturis haerent, vera esse peccata: falsum est tamen eandem de peccatoribus fidelibus, quam infidelibus esse rationem. Hoc ipso enim quo peccatores fide imbuti sunt, quanquam perfecta illa charitate Deum super omnia diligente, hoc est, justificatione, destituti sint, multa tamen bona ex illa fide operari possunt; sicut in primis ipsum credere & operari velle, & si adhuc viribus careant, infirmitatem suam ingemiscere, ex fide justificationem, vel operandi vires impetrare, cujusmodi opera Augustinus semper peccatoribus tribuit. Et postea probare volens fideles quantislibet peccatis mancipatos non carere imperfecto quodam amore Dei, qui sincerus tamen sit & verae pietatis initium, quali Dei amore carent prorsus infideles, Hoc ipso, inquit, quo adhuc fideles permanent, non possunt non habere affectum illum verae pietatis atque dilectionis, ex quo credunt Deo, ex quo sperant subinde beatitudinem, ex quo orant pro impetranda perfecta charitate, atque justitia; ex quo etiam alia nonnulla bona sincero Dei intuitu operantur, quamvis necdum ita diligant, ut eum omnibus terrenis amoribus, ac delectationibus praeferant.